1. Field of the Invention
The present invention relates to a fracture surface treatment method and a fracture surface treatment apparatus for treating fracture surfaces made by tension-fracturing a ductile metal part such as a connecting rod or the like for example, and a manufacturing method and a manufacturing apparatus of a ductile metal part being fractured and having its fracture surfaces treated.
2. Description of the Related Art
There is a case of tension-fracturing a ductile metal part, and recombining together the halved part portions into a single product to be used. As an example of such parts, a connecting rod known as one of car parts is mentioned. And as a method for separating a larger end portion of a connecting rod into two parts, namely, rod and cap portions, there is a so-called fracture splitting (FS) method. An example of such an FS method applies a pre-load to a mandrel by pressing a wedge against the mandrel and then applies a dynamic load to it and thereby fractures a connecting rod (see Japanese Patent Laid-Open Publication No. 2002-66,998 for example).
Further, there is also known a fracture surface treatment method for treating fracture surfaces of such a fractured connecting rod. Concretely, for example, there is known a fracture surface treatment method for removing material particles (fracture powder) from fracture surfaces in case of separating members such as a connecting rod, a bearing, an annular enclosure and the like by fracture (see Japanese Patent Laid-Open Publication No. 2003-512,522 for example).
In addition to this, there is also known a fracture surface treatment method for making it easy to separate the recombined connecting rod obtained by recombining and machining a fractured connecting rod into a connecting rod main body portion and a bearing cap portion, and thereby improving the assembly-operability in assembling them into an engine (see Japanese Patent Laid-Open Publication No. 2000-74,067 for example).
A fracture surface treatment method of a fractured connecting rod described in Japanese Patent Laid-Open Publication No. 2003-512,522 is a treatment method for removing particles having no or little adhesiveness (hereinafter, referred to as fracture powder) from fracture surfaces, and operates a controller and thereby makes a cylinder reciprocate.
Concretely, this method reciprocates the cap of a connecting rod by reciprocating the piston of a cylinder. And the method removes fracture powder from fracture surfaces by adjusting the range of this reciprocation so that the cap comes slightly into contact with the fracture surface of the connecting rod during the reciprocation of the cap.
However, since in such a fracture surface treatment method of a connecting rod the direction of vibration of the cap coincides with the direction of fracture of the connecting rod and such vibration that the cap comes slightly into contact with the fracture surface of the connecting rod is applied, a part of fracture powder is stripped off but the remaining part is firmly stuck onto the fracture surface by such a touching operation, and it is thought to have a bad influence on the face fitting operation of fracturing surfaces after that.
On the other hand, a fracture surface treatment method of a connecting rod described in Japanese Patent Laid-Open Publication No. 2003-512,522 is a method for making it easy to separate the recombined connecting rod obtained by recombining and machining a fractured connecting rod into a connecting rode main body portion and a bearing cap portion. Concretely, this method repeats three or more times an operation of applying and releasing a load to and from the connecting rod main body portion having the separated bearing cap portion attached to it before machining the recombined connecting rod obtained by recombining together the connecting rod main body portion and the bearing cap portion after fracture-separating the bearing cap portion from the connecting rod main body. However, performing only such an operation of pressing the fracture surfaces against each other makes part of fracture powder adhere firmly to the fracture surface of the connecting rod and it is thought to have a bad influence on the face fitting operation of the fracture surfaces after that.